Olivet University - Olivet Institute of Technology

Google PageRank checksum PHP algorithm revealed

In a blog entry, the Google PageRank checksum algorithm was revealed.

The Google PageRank functionality in Google Toolbar works by querying Google’s server for information on the PageRank of a specific page. This might seem easy enough to implement in your own program/website, but the problem is that the toolbar calculates a checksum on the page URL before querying the server, and the server only responds if the checksum is correct. Fortunately the checksum algorithm was reverse engineered from Google Toolbar 7. I was provided the hand decompiled version of the algorithm in C from a friend. Then I went ahead and rewrote it in PHP for web development usage. You can find both versions below.

As an example, the query URL for the page ‘http://en.wikipedia.org/wiki/Cypherpunk’ is http://toolbarqueries.google.com/tbr?client=navclient-auto&features=Rank&q=info:http://en.wikipedia.org/wiki/Cypherpunk&ch=783735859783

Any other query with a checksum other than 783735859783 will result in a ‘403 forbidden’ response.
Enjoy.

PHP CODE:

<?php

/* the floating point hacks are due

   to PHP's bugs when handling

   large unsigned integers */

functionfch($csm)

{

    if($csm< 0)

        $csm+= 4294967296.0;

    $a= (int)fmod($csm, 10);

    $t= 1;

    $b= (int)($csm/ 10);

    while($b) {

        $c= $b% 10;

        if($t)

            $c= (int)($c/ 5) + ($c* 2) % 10;

        $b= (int)($b/ 10);

        $a+= $c;

        $t^= 1;

    }



    $a= 10 - $a% 10;

    if($a== 10)

        returnord('0');



    if($t)

        returnord('0') + (int)(($a& 1 ? $a+ 9 : $a) / 2);

    returnord('0') + $a;

}

functionchecksum($str)

{

    if(strlen($str) == 0)

        return0x1000;



    /* the floating point hacks are due to PHP's bugs when handling integers */

    $a= 5381.0;

    for($i= 0; $i< strlen($str); $i++)

        $a= fmod($a+ ($a* 32) + ord($str[$i]), 4294967296.0);

    if($a> 2147483647.0)

        $a-= 4294967296.0;

    $a= (int)$a;

    $b= 0.0;

    for($i= 0; $i< strlen($str); $i++)

        $b= fmod(($b* 64) + ($b* 65536) - $b+ ord($str[$i]), 4294967296.0);

    if($b> 2147483647.0)

        $b-= 4294967296.0;

    $b= (int)$b;



    $a= (($a>> 6) & 0x3ffffc0) | (($a>> 2) & 0x3f);

    $c= (($a>> 4) & 0x3ffc00) | ($a& 0x3ff);

    $d= (($c>> 4) & 0x3c000) | ($c& 0x3fff);

    $c= ((($d& 0x3c0) << 4) | ($d& 0x3c)) << 2;

    $a= $b& 0x0f0f;

    $e= $b& 0x0f0f0000;

    $b= (($d& 0xffffc000) << 4) | ($d& 0x3c00);

    return($b<< 10) | $c| $a| $e;

}

$PR_SERVER= "http://toolbarqueries.google.com/tbr?client=navclient-auto&features=Rank&q=info:";

$page= "http://en.wikipedia.org/wiki/Cypherpunk";

$csm= checksum($page);

printf($PR_SERVER. "%s&ch=7%c%u\n", $page, fch($csm), $csm);

?>

The author of the PHP code is Dmitry Molotov.

Posted 9 months ago

2 notes

google, pagerank, developer, engineering, php, web development,

NetBeans IDE 7.2: Smarter & Faster

NetBeans IDE 7.2 is alive! The NetBeans IDE 7.2 release comes with significantly improved performance and many new features in the Java Editor, with a special focus on FindBugs integration, providing new static code analysis capabilities.

Along with a vastly improved developer experience that helps you write good, bug-free code quickly, it also delivers improvements in other areas, notably in its support for JavaFX, Java EE, Maven, PHP, and Groovy.

Read all the review at DZONE.

Posted 9 months ago

1 note

netbeans, computer programming, javascript, php, java, editor,

Javascript Development tips

Javascript language is known to be a very flexible language in terms that it doesn’t enforce too many rules on developers, deferring from Java or C# very much.

Still, there are some good basic rules that should be kept to ensure that your code has the capability of being extended and maintain consistency overtime.

Some of the rules discussed by Honza in a recent blog post are very relevant, and we are going to post them here with explanation:

Naming conventions - Very difficult of navigating and maintaining a code where the naming conventions are not clear. Also it should allow a clear distinction of the type of variable through its name.
File dependency - Documenting your code in a way that specifies the dependencies the code relies upon.
Class definition time and consumption time - Clear distinction between the time of definition and the time of consumption (the time the app begins).
Namespaces - Using namespaces to organize your code.
Documentation - There is no much need to explain this point upon the situation of a new developer joining the team and having to understand undocumented code made by other developers.
Frameworks - If you’re using a framework, always respect the framework’s guidelines and conventions so that the framework documentation can be used to understand your project.

Also you can read more regarding modular Javascript:

Writing Modular JavaScript With AMD, CommonJS & ES Harmony - http://addyosmani.com/writing-modular-js/

Why AMD - http://requirejs.org/docs/whyamd.html

Posted 10 months ago

developer, javascript, web development, web 2.0, jquery, methodology, php, engineer, engineering,